Gas:Oil Ratio Question

[bds85466]

So I'm sure nobody -- well most people -- do not get out a graduated cylinder and measure their ratios as they're filling up the tank, so my question is this: How accurate is accurate enough when it comes to your premix?

Given a couple things:

Most of the time I fill my gas tank, using the gasoline gallon read-out, plan accordingly with the 2 stroke oil, using the conversion on the back of the bottle. Now there's only graduations at every so many ounces on the oil and it's completely guesswork as far as I'm concerned.

After many times of filling your tank like this, could this make a difference? Depending on how much oil you're over or underestimating? Does one or the other tend to "stick" (oil and gas that seperate?) in the gas tank?

How much deviation matters when it comes to actual engine performance? What happens (what sort of immediate symptoms arise) when deviation goes out of "tolerance" in either direction? If it came down to it (obviously it's best to get it right on), is it better to overestimate, or underestimate your ratio?

 

[hitace]

Re: Gas:Oil Ratio Question

i use 2 gas tanks the one i use to fill with premix (6 gal) and the one i use for the outboard(4 gal) i just empty 1 or 2 gallons from the storage gas tank to the one i use for the outboard and when the 6 gal tank is empty I know exactly how much gas and oil to put in it.

 

[Dhadley]

Re: Gas:Oil Ratio Question

Well, "back in the day" before oil injection I got pretty good at figuring out what we used. If I figured it would take 15 gallons to top off (not an empty tank) I'd put in enough oil for 15 gallons (yes I used a measuring bottle). If it took 12 or 13 it was no big deal. It it took 16 I just added a bit.

Thank goodness I don't have to worry about that anymore!

 

[Cricket Too]

Re: Gas:Oil Ratio Question

I pre-mix a 60 gallon gas tank, I just use a measuring bottle, you can get them at any marine store. They have lines on the side for gallons fo gas, for any ratio, and you fill to say the 10 gallon mark, then you know your good for 10 gallons and so on.

I usually fill up 30 gallons when I get to about a 1/4 tank, so I just fill up to the 10 gallon mark 3 times then put 30 gallons in, no problem.

If your using any good oil (TCW-3 certified) and you use your gas pretty regularly, the fuel and oil won't separate. If you let it sit for 3 years, the oil may start to gel, but you gas would be unusable at that point anyway.

Your gas doesn't care whether it is mixed at 25:1 or 100:1, it's not concerned, it's your engine that requires 50:1, so extra oil won't come out of the gas and "stick" in the tank.

 

[bds85466]

Re: Gas:Oil Ratio Question

I use the same tank every time. Would it be wise to empty the thing say once a year and start from scratch? How can I safely dispose of everything left in the tank?

 

[Cricket Too]

Re: Gas:Oil Ratio Question

I don't think there's really any need to, just use fuel stabilizer when your storing it, and you should be good. If you do want to dump it for whatever reason, I would say you would have to take it to your local landfill to dispose of it properly.

 

[dajohnson53]

Re: Gas:Oil Ratio Question

For what it's worth, I personally don't think minor variations from 50:1 affect performance or engine life for recreational use.

I have two 24 gallon built in tanks. I never measure oil more accurately than pints (e.g. 1/2 quart) of oil. I do not use a graduated cylinder. I just keep quarts on board and dump in either full or half bottles. I have what I think is a common sense approach, and thinking about it, here is how it plays out.

Of course 1 pt is for 6 gallons so anything in 6 gallon increments is right on, therefore full tank fill ups and any increment of 6 gallons are totally accurate.

I tend to stop at 6 gallon increments rather than top off.

The only time it is inaccurate at all is rare occasions I top off completely and the last bit is not exactly 6 gallons. This is is "almost always" in an amount that is closer to 6 gallons than 1 gallon because I don't bother topping off if the tank is almost full. So, it's 3, 4, 5 gallons and I treat it as 6, so the error is on the side of a little rich, but diluted with the existing gas, therefore hardly rich at all.

On the even more rare occasions I top off and it's only 1-2 gallons, I don't bother to put in additional oil, again, because it's diluted with an almost full tank of 50:1, the effect is almost nothing. If you add to this fact, the fact that almost all other inaccuracies are on the side of rich, the net effect is 0.

I've done this for many years with my built in tanks and have never had a fuel related problem (every damn problem I've had with this engine is ignition related, that's a different story). As I write, I'm having an oil injected engine rigged on my boat, so my pre-mixing days are numbered!

I tend to think the seemingly exact spec for 50:1 is actually based at least somewhat arbitrarily on the US system of liquid measurements. In the US it's actually 48:1 gasil, what is it in metric countries? How is oil packaged, 500cc?

 

[BoatBuoy]

Re: Gas:Oil Ratio Question

Don't stress over the mix ratio. It's not chiseled in stone or finitely calculated by some engineer. JohnnyRude used to recommend 100:1 until they discovered there wasn't enough residual oil to protect engine parts during down time. Mix whatever you need at 50:1 +/- 50% and don't worry. Close is good enough. If concerned, give it an extra shot of oil.

 

[pecheux]

Re: Gas:Oil Ratio Question

Can 50:1 premix be used in vehicules ?? If so it would be a fine way to dispose of OB gas tanks leftover come winter time ... and start fresh in spring ...

Cheers

 

[dajohnson53]

Re: Gas:Oil Ratio Question

Can 50:1 premix be used in vehicules ?? If so it would be a fine way to dispose of OB gas tanks leftover come winter time ... and start fresh in spring ...Cheers

I am NO expert, so please use your own judgement. I have put my oldish premix into my '86 Chevy pickup (carb). I try to dilute it at least 50:50. I also use it in my lawnmowers, etc. I don't know if it would harm modern FI engines, but I doubt it would, especially if diluted.

Better yet, is use the gas as an excuse to go for a long boat ride in the fall before you put the boat up for the winter.

 

[bds85466]

Re: Gas:Oil Ratio Question

All good posts. Thanks! Does anyone notice a difference in their performance when they mix on the thin or thick side?

 

[Cricket Too]

Re: Gas:Oil Ratio Question

You won't notice much of a performance difference between a 60:1 or 40:1 mixture, like was said above, don't stress it too much, close is good enough. ifyour really concerned buy a $5 mixing bottle and you will as close as you can get to 50:1.


The biggest problem with running any pre mix through your vehicle is gonna be with the O2 sensors and catalytic converter, they won't like the oil being burned. An old carbed truck will eat it no problem, but I wouldn't risk it on anything newer.

Lawnmowers and such are air cooled engines, if you run too much TCW-3 through them it will start to hurt them. Air cooled 2 stroke oil is made to run at higher temps than TCW-3.

 

[pecheux]

Re: Gas:Oil Ratio Question

You won't notice much of a performance difference between a 60:1 or 40:1 mixture, like was said above, don't stress it too much, close is good enough. ifyour really concerned buy a $5 mixing bottle and you will as close as you can get to 50:1.


The biggest problem with running any pre mix through your vehicle is gonna be with the O2 sensors and catalytic converter, they won't like the oil being burned. An old carbed truck will eat it no problem, but I wouldn't risk it on anything newer.

Lawnmowers and such are air cooled engines, if you run too much TCW-3 through them it will start to hurt them. Air cooled 2 stroke oil is made to run at higher temps than TCW-3.

Thanks for the feedback. Yep I go a full tank of premix that wont be used since the river ran almost dry where I live so my boating season is over ... Water level is at an all times low since 1926 they say ... ha well ... will get those golf clubs cleaned up ... LOL

Will burn that gasoline in the snowblower ... lol dont like to use tc-w3 in a lawnboy mower ... gets too hot.

Cheers,